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Tire Rolling resistance(8 posts)

Tire Rolling resistanceLC
Oct 4, 2001 10:19 AM
Some people claim that wider tires have less rolling resistance, but I don't know what to think now. I am sure a few people will find some interesting info here:

http://www.terrymorse.com/bike/imgs/rolres.gif
re: Tire Rolling resistanceTig
Oct 4, 2001 10:52 AM
I might be wrong, but I feel that narrower tires can have lower rolling resistance than wider ones. The reason? Higher tire pressure. The maximum recommended tire pressure for higher volume tires is usually lower than 23c's. If I put 110 PSI in some 28's vs. 125 in my 23's, I should have a harder tire with less rolling resistance. Also the lighter rotating mass is easier to accelerate and climb with. Like I said, I could be wrong!

I DO know that smaller diameter tires have higher rolling resistance. My old track bike was made by a local builder who tried to make a name for himself using 24" wheels. The smaller wheels were much more aerodynamic than 700c's, but they lost more speed to the rolling resistance of the smaller circumference and shorter "cigar" contact patch, especially when on the rough surface of the roads.

However, the smooth surface of a velodrome, even concrete ones nullified that problem. These small, super light aerodynamic wheels (tubulars of course) accelerated like rockets! Perfect for a multipurpose track bike.
re: Tire Rolling resistanceJofa
Oct 4, 2001 11:32 AM
The graph tells it all, really. There are a few variables at play, which counteract one another to varying extents. All else equal, slightly wider tyres generally roll slightly better: of course, this doesn't follow indefinitely- or we'd all be riding Hanebrink sand bikes. There's casing construction, tread thickness and pattern, tube thickness, and tyre pressure to be considered. Not forgetting aerodynamics, in the larger picture.

All of it's mostly academic anyway is nobody would be able to know what kind of tyres are on their bike without looking.
Full disclosuremr_spin
Oct 4, 2001 3:43 PM
Brandt, the guy who apparently did the test, is the "inventor" and biggest advocate of the Avocet tires. Not that he's wrong or evil or anything.
So?Kerry Irons
Oct 4, 2001 4:34 PM
This chart shows that for nearly all tire models, the larger tire (at the same pressure) has lower rolling resistance. This is widely known and easily explained. The size of the contact patch on the road is (exactly) the weight on the tire divided by the pressure. A larger section tire has to deflect less, and so has lower rolling resistance. Narrower tires are normally pumped harder, so this effect tends to cancel. So what's new? (Note that these tires are all about a decade old).
Southern Comfortbreck
Oct 4, 2001 6:21 PM
Resistance aside, narrow tires will beat you up on rough mountain roads, esp. if you have stiff "aero" wheel set. OK for time trials & shorter races though. And some road tires just seem to be "hard riding" no matter the size, pressure, etc.

Here in the mountains us older guys opt for Conti GP 25's aired down to about 100psi front non-aero 28 spoked 3X db wheel; rear 32 ditto, but 110psi. Seems the younger guys just have-to-have the narrow tires, aero wheel set," re-call light" bikes, etc. and claim they are faster ...and they are :)

It may all boil down to compromise, etc.

cheers,
breck
New topic: Old-guy rolling resistanceElefantino
Oct 4, 2001 7:28 PM
I'm 43, 6-5, 210. I think I have a wider contact patch than someone who's 5-8, 140. But I seem to go downhill faster. And darned if the 5-8 140s don't always seem to want to draft behind me.

What is the scientific term for that?
Let's not get into this physics discussion again--ughhhh (nm)Chris Zeller
Oct 5, 2001 7:25 AM